ENGLEWOOD, Colo. -- When the Denver Broncos take to the practice field Monday, wide receiver Wes Welker will not be among those players in uniform.

And while the Broncos, after some testing in recent days, don't initially believe Welker's concussion is as serious as the two he suffered last season, he is still under the league's concussion protocol.

That means even if Welker was symptom free on Sunday -- and according to some with the team he was not -- he cannot resume full duties in practice until five days after the hit that caused the injury. Welker left Saturday's preseason game with nine seconds remaining in the first half after taking a blow to the helmet from Houston Texans safety D.J. Swearinger. Welker got up and walked, next to a member of the Broncos training staff, off the field and straight into the locker room.

This makes the third time Welker has been under the guidelines of the league's concussion protocol since Nov. 17. He left a game on that date against the Kansas City Chiefs, was reported by the team to have a concussion when he left a Dec. 8 game against the Tennessee Titans and then Saturday's game. Broncos head coach John Fox seemed to dispute the number of concussions Welker has suffered immediately following the game.

When asked if the league's concussion protocol changes for a player who has had multiple concussion, Fox answered: "I don't know about multiple ones a year ago but, again, not being a doctor, I will leave that to the medical people and he won't come back until he's ready to come back."

Fox will speak publicly about Welker's status Monday afternoon, following the team's practice. Welker was held out of the final three games of the regular season in 2013, but did return last season to play in the Broncos' three postseason games, including Super Bowl XLVIII. He wore a helmet with extra padding in those games, and he has continued to wear the helmet this preseason.

To play in the Sept. 7 regular-season opener against the Indianapolis Colts, Welker would likely have to be symptom free by Monday.

According to the league's concussion protocol, even if a player is symptom-free the day following his concussion, he can return only to light exercise three days after the hit and only in non-contact portions of practice four days after the hit.

The quickest a player, who is symptom free the day after suffering the concussion, can return to a full contact practice is five days after the hit, which is Friday in a normal game week.

Also per the policy, once a team doctor has signed off on a player's return to the field, a doctor unaffiliated with the team and approved by both the NFL and NFL Players Association must also clear the player to return. One of the factors considered, in addition to the cognitive tests, is a player's concussion history.